Players of electric musical instruments, notably electric guitars, strive to obtain particular tonal qualities from their instruments. For example, guitar players often overdrive amplifiers to achieve harmonic distortion, which is desirable in various musical contexts. Generally, such distortion can be generated by overloading an audio signal in a preamplifier (“preamp distortion”) and, thereafter, amplifying the distorted audio signal simply to make it louder and without further affecting its tone. In addition (or in the alternative), distortion can be generated by overloading a signal in the amplifier itself (“power amp distortion”), as opposed to the preamplifier. Power amp distortion usually requires an extremely high volume level to be achieved, and thus is not as practical for many players as preamp distortion, which can generate distortion at a low volume. Despite the practical limitations, power amp distortion is often considered more desirable, as it produces tonal qualities having a greater dynamic range and can be controlled more effectively than preamp distortion by the player, such as by using various playing techniques. Guitar players often prefer power amp distortion for being more “responsive” or “touch sensitive” than preamp distortion. Further, most vintage (e.g., tube) guitar amplifiers produce only power amp distortion, and players prefer the sounds that such devices produce over more recent or modern guitar amplifiers, which rely largely or exclusively on preamp and/or digitally produced distortion.
In addition to the sounds produced by preamp distortion and power amp distortion, players of electric guitars and other electric instruments employ devices to produce other sound effects to alter tones and sounds that emanate from their instruments. Referred to herein generally as “wet effects,” these devices can include signal boosters, distortion devices and equalizers, and are designed to receive a line level output signal from an instrument (e.g., guitar output) and send a modified line level signal to the input of the amplifier. Wet effects can further be classified as “time-based” effects, and produce reverb (e.g., echo), delay (e.g., repeating), pitch alteration, and other sound qualities that are not intended to alter the basic sound of an amplifier, but to add sound-based functionality to an amplifier. For example, a wet effects unit can produce reverb for a vintage amplifier that is not configured with that effect. Wet effects can be provided in analog and/or digital devices, and can be configured in various formats, such as foot pedals, hand-held devices (including mobile computing devices), or in rackmount devices that can include rocker switches, push buttons, knobs, slider controls and/or other controls.
Many players of electric instruments believe that the order in which various effects are connected, such as “in front of” or “behind” an amplifier greatly affects tonal quality. For example, some wet effect units should not receive a signal from the instrument to provide a reverb effect as input to the amplifier. A signal producing reverb, for example, is believed to suffer in tonal quality when it is overdriven in the amplifier or subjected to power amp distortion. It is often preferred for an audio signal to be overdriven (i.e. distorted) and, thereafter, shaped to include reverb, delay or other wet effect.
Some musical instrument amplifiers are configured with a preamplifier and amplifier, and often include wet effects that are positioned between the preamplifier and the power amplifier. Referred to, generally, as an “effects loop,” such amplifiers are configured such that the wet effects operate on audio signals that are distorted via preamp distortion, and made louder by the amplifier. Other musical instrument amplifiers are not so configured, and may not work well with effects loops because the time-based effects are positioned after the preamplifier, and the audio signals processed by wet effects get further distorted as the power amplifier is overdriven (i.e., by power amp distortion).